JP2009197371A - Method for producing paper and the paper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing paper which does not impair the effects of improving its opacity or whiteness obtained by adding a filler, is capable of improving the yield(s) of a filler and/or paper-making chemicals in its paper-making process, and is capable of obtaining the paper of uniform filler distribution, and to provide the paper produced by the method. <P>SOLUTION: The method includes the following steps: a first paper-making material prepared by mixing first pulp having scale-like external fibril and a filler and/or paper-making chemicals, is blended in a second paper-making material containing second pulp other than the first pulp, and paper is produced. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention can improve the yield of fillers and / or papermaking chemicals in the paper making process, and at the same time, does not impair the effect of improving the opacity and whiteness of the paper by blending the filler, and the filler distribution The present invention relates to a paper manufacturing method capable of obtaining a uniform paper and a paper obtained by the manufacturing method.

  For the purpose of improving paper quality, it has been conventionally practiced to internally add fillers and various papermaking chemicals to paper stock containing pulp as a main component during papermaking. The purpose of adding a filler is to improve the opacity, whiteness, printability, etc. of the paper. Particularly in recent years, attempts have been made to produce paper with a high filler filling rate from the viewpoint of resource saving as well as quality improvement. However, since the filler is significantly smaller than cellulose fibers, the yield to the paper web is low in the paper web formation stage on the paper machine wire. This decrease in yield causes an increase in the filler concentration of the paper machine white water system, which causes a deterioration in operation efficiency. Therefore, a technique for efficiently retaining more filler in the paper web is required. Further, in order to increase the filling rate of the paper into the filler, it is necessary to add a large amount of filler to the pulp fiber and bind these fillers to the fiber with various yield chemicals. In order to bind a large amount of filler to the fiber, it is necessary to add a large amount of yield chemicals. As a result, the filler and the pulp form a large agglomerate, which causes a problem of impairing the formation of the paper.

  As one of the methods for improving the filler yield, it is known that increasing the specific surface area of the pulp is effective. Specifically, if the raw pulp is highly beaten, the freeness is lowered to increase the fine fibers, and the fine fibers can be efficiently mixed with the long fibers into the paper, the filler yield is improved. However, in reality, an increase in the amount of fine fibers and an increase in the release amount of substances that interfere with the yield called anion trash from the fibers due to beating occur, and an increase in the amount of chemicals required for a certain yield and an increase in the number of fine fibers cause a paper loss. Decrease in transparency becomes a problem.

  One countermeasure against such a problem is so-called filler pretreatment. In this method, the filler is agglomerated in advance with a flocculant, and this is added to the pulp fiber for paper making. For example, pH adjustment with acid or base, addition of inorganic flocculant such as aluminum sulfate, organic polymer flocculant Is shown (Patent Document 1). In addition, a method of pretreating calcium carbonate particles mainly with an organic polymer flocculant such as pH adjustment, inorganic flocculant, polyacrylamide, etc. (Patent Document 2), and processing by mixing heavy calcium carbonate with an aqueous cation-modified starch solution Method (Patent Document 3), Method of agglomerating calcium carbonate using cationized starch and cationized guar gum, (Patent Document 4), After treating calcium carbonate with a cationic polymer, anionic fine particle material Examples of the adding method (Patent Document 5) and the flocculant for pre-aggregating the filler include water-soluble vinyl polymer, gum, polyacrylamide, aluminum sulfate, mannogalactan, anion-modified starch derivative, esterified starch and the like (patent) References 6 and 7). However, although these filler pretreatment methods are effective as a method for efficiently yielding the filler, new problems such as a decrease in opacity due to agglomeration of filler particles and a decrease in whiteness in some cases. Cause.

  As a method for suppressing the decrease in opacity due to the pretreatment of the filler, a method of aggregating the fine fiber of the pulp and the filler with a flocculant is disclosed (Patent Documents 8 and 9). However, in these methods, it is necessary to use fine fibers of pulp that passes through a 150 mesh wire, and a special separation operation is required, resulting in low production efficiency.

Japanese Patent Publication No.57-13680 Japanese Patent Laid-Open No. 54-116405 JP-A-60-119299 Japanese Patent Laid-Open No. 10-60794 Special Table 2000-504790 Japanese Unexamined Patent Publication No. 2000-129589 JP 2006-118092 JP Japanese Patent Publication No. 6-70317 Japanese Patent Publication No. 6-94639

  As described above, the yield of the filler and / or papermaking chemicals can be improved in the paper making process, and at the same time, the effect of improving the opacity and whiteness of the paper by the filler blending is not impaired, and the filler Development of a new yield improvement technique that can obtain paper with a uniform distribution has been desired.

  An object of the present invention is to efficiently produce a pulp having external fibrils having a large specific surface area, and use this to efficiently bind a filler and / or papermaking chemicals to long fibers, so that the filler and / or papermaking in the paper making process. A method for producing paper that can improve the yield of chemicals for use, and at the same time, does not impair the effect of improving the opacity and whiteness of the paper by blending the filler, and can obtain a paper having a uniform filler distribution, And providing the paper produced by the production method.

  In order to increase the specific surface area of the pulp, the inventors used the idea opposite to increasing the fine fibers. That is, in order to increase the specific surface area of the pulp, as a result of earnest research on the method of increasing the specific surface area of the long fibers while suppressing the generation amount of fine fibers, pulp having scale-like external fibrils, fillers and / or papermaking chemicals It was found that the above-mentioned problems can be solved by blending the papermaking raw material prepared by mixing with the papermaking raw material containing pulp other than the pulp having the scale-like external fibrils. In particular, a pulp having scale-like external fibrils obtained by generating bubbles by cavitation in a pulp suspension in a reaction tank and applying an impact force generated when the bubbles collapse to pulp fibers, and a filler and It has been found that the above-mentioned problems can be solved by blending papermaking raw materials prepared by mixing papermaking chemicals with papermaking raw materials containing pulp other than pulp having scale-like external fibrils.

The papermaking raw material prepared by mixing the pulp having the flaky outer fibrils of the present invention and the filler and / or papermaking chemicals is blended with the papermaking raw material containing pulp other than the pulp having the flaky outer fibrils. By making paper, the following effects can be obtained.
1) The yield of fillers and / or papermaking chemicals can be improved in the paper making process.
2) By improving the yield of the filler, the effect of improving the opacity and whiteness of the paper by blending the filler is not impaired.
3) Since the filler can be uniformly fixed in a state of being dispersed in the external fibril part, a paper with high opacity and whiteness and uniform filler distribution can be obtained.
4) It is possible to reduce the amount of the yield improver added to improve the yield of the filler, thereby further improving the texture of the paper.
5) Since the filler is taken into the fibrils and held more firmly on the paper, the filler drop and paper dust troubles are reduced.

  The present invention relates to a papermaking raw material prepared by mixing a pulp having scale-like external fibrils with a filler and / or papermaking chemicals in order to improve the yield of the filler and / or papermaking chemicals on the wire of the papermaking machine. Is added to and mixed with a papermaking raw material containing pulp other than the pulp having scale-like external fibrils.

  The pulp having scale-like external fibrils used in the paper manufacturing method of the present invention will be described below. The raw material pulp of the pulp having scale-like external fibrils is a fibrous material mainly composed of cellulose obtained from wood, and is made of chemical pulp fibers such as coniferous and hardwood kraft pulp, sulfite pulp, softwood and hardwood. Examples thereof include mechanical pulp fibers such as crushed pulp, refiner crushed pulp, thermomechanical pulp, and chemithermomechanical pulp, and recycled pulp fibers derived from a sheet-like substance made of waste paper or fiber. These pulps may be used alone or in combination.

  The pulp used in the present invention is characterized by having scaly external fibrils. The external fibrils in the form of scales are peeling or fluffing of the fiber surface having a width of 3 μm or more, and preferably about the same as the width of the fiber, and the above-mentioned microfibrils are connected side by side. Thus, an aggregate is formed to form a wide layer, and the microfibrils on the fiber wall surface are peeled off while maintaining the layer structure. Further, the thickness is in the range of 90 Å to 2 μm. When observing the fiber with an electron microscope, it is desirable to perform measurement in a dry state in which hydrogen bonding is inhibited. However, when the fiber is simply dried, external fibrils are drawn on the fiber surface by capillary action. Therefore, it is difficult to accurately observe such fibrils.

  The scaly external fibrils in the present invention are characterized by being dyed with a high molecular weight dye having a molecular weight of 10,000 or more. As dyes having a molecular weight of 10,000 or more, Simon et al. (FL Simons, Tappi, 33 (7), 312 (1950)) and Xiaochun et al. (Y. Xiaochun et al., Tappi Journal, 78 (6) , 175 (1995).) Orange dyes such as CI Constitution no. 40000-40006 including Direct Orange 15 (old Color Index (CI) no, 621, or CI Constitution no. 40002/3) However, there is no particular limitation as long as it is a substance that can dye fibers mainly composed of cellulose.

  According to Xiaochun et al., The above-mentioned dye having a molecular weight of 10,000 or more is a molecule having a hydrodynamic size of 5 nm or more from light scattering measurement, and cannot penetrate into pores of less than 5 nm existing on the surface of pulp fiber. . On the other hand, fibrils composed of aggregates of microfibrils on the surface of pulp fibers are exposed to the outside of the pulp fibers, so that the dye molecules having the molecular weight of 10,000 or more can be easily approached. The part can be selectively stained.

F.L.Simons, Tappi, 33 (7), 312 (1950). Y. Xiaochun et al., Tappi Journal, 78 (6), 175 (1995).

  In order to optically emphasize and observe the fibril part, Direct Blue 1 (old Color Index (CI) no.518 or CI Constitution no.24410), Direct Blue 4, By dyeing the entire fiber with a low molecular weight dye such as Direct Blue 15, Direct Blue 22, or Direct Blue 151, you can observe with more contrast. Although low molecular weight dyes are adsorbed to the entire fiber, high molecular weight dyes have stronger adsorption power, and therefore, low molecular weight dyes are substituted. As a result, it is possible to dye fibril parts that can adsorb high molecular dyes (orange dyes) in orange and dye fiber pores that cannot adsorb high molecular dyes with low molecular dyes (blue dyes). Therefore, the fibril portion can be emphasized. The low molecular weight dye contains 51% or more of molecules having a molecular weight of less than 10,000, preferably less than 2000, and more preferably 300 to 1500.

  After the pulp having scale-like external fibrils of the present invention is dyed by the above-described method, the area of the scale-like external fibrils represented by the following formula 1 is 5% or more with respect to the area of a certain number of fibers. It is preferable that

  Further, in the unit of one pulp fiber, the area ratio of the external fibril part represented by the following formula 2 is 7% or more, and the peripheral length ratio of the external fibril part represented by the following formula 2 is 1.5 or more. It is preferable. Since the scale-like external fibrils of the pulp fiber of the present invention have a larger surface area than ordinary fibrils, these values are increased.

The pulp used in the present invention, especially wood pulp, is characterized by a low water retention when compared with the same Canadian standard freeness of pulp that has been beaten by a conventional method and advanced to internal fibrillation. In the pulp having scale-like external fibrils of the present invention, the relationship between the water retention (X) and the Canadian standard freeness (Y) is approximated by the following formula 3.

Canadian standard freeness reflects the wetness of the entire fiber, and water retention reflects the wetness of the fiber. Therefore, when compared with the same Canadian standard freeness, the pulp of the present invention does not progress in internal fibrillation as compared with the pulp beaten by a normal method, so the water retention is low. Water retention is measured by the method specified in JAPAN TAPPI No.26: 2000.
As a method for obtaining the pulp having scale-like external fibrils of the present invention, any method may be used. For example, shear force and cavitation rather than mechanical beating treatment such as cavitation jet treatment (Japanese Patent Application No. 2005-321231). It can be easily obtained by using a method of promoting external fibrillation by the collapse energy of bubbles.

  The cavitation jet treatment will be described in more detail. By actively introducing bubbles generated by cavitation into the pulp suspension, the external fibrillation of the pulp fibers is promoted by the impact force when the fine bubbles collapse, The freeness is adjusted by suppressing internal fibrillation.

  The reason why external fibrillation is promoted by the decay energy of cavitation bubbles is considered as follows. When fine bubbles generated by cavitation collapse, strong energy is generated in a local region on the order of several μm as described above. Therefore, when a fine bubble or bubble cloud collapses on or near the surface of the pulp fiber, the impact force reaches the fiber surface directly or through a liquid and is absorbed by the amorphous region of cellulose constituting the fiber. This is considered to cause external fibrillation and fiber swelling. Bubbles are very small on the fiber and its impact force is not so great as to damage the entire fiber. Further, since the fibers are dispersed in the liquid and are not fixed, excessive energy is absorbed as the kinetic energy of the fiber itself even with a very large impact force such as continuous collapse of a bubble cloud. Therefore, it is considered that damage such as fiber shortening can be suppressed and internal fibrillation can be suppressed as compared with a beating method using a mechanical action.

  Examples of the cavitation generating means in the present invention include a method using a liquid jet, a method using an ultrasonic vibrator, a method using an ultrasonic vibrator and a horn-shaped amplifier, and a method using laser irradiation, but are not limited thereto. It is not something. Preferably, the method using the liquid jet has a high effect on the pulp fiber because the cavitation bubble generation efficiency is high and a cavitation bubble cloud having a stronger collapse impact force is formed. The cavitation generated by the above method is clearly different from cavitation that causes uncontrollable harm that naturally occurs in conventional fluid machines.

  In the present invention, when cavitation is generated using a liquid jet, the pulp suspension and bubbles can be brought into contact with each other by jetting the pulp suspension as a liquid jet. In addition, the fluid in which the liquid jet forms a jet may be liquid, gas, solid such as powder or pulp fiber, or a mixture thereof as long as it is in a fluid state. Further, if necessary, another fluid can be added as a new fluid to the above fluid. The fluid and the new fluid may be uniformly mixed and ejected, but may be ejected separately.

  The liquid jet is a jet of a fluid or a fluid in which solid particles or gas are dispersed or mixed in the liquid, and refers to a liquid jet containing slurry of pulp fibers or inorganic particles or bubbles. The gas referred to here may include bubbles due to cavitation.

  Since cavitation occurs when a liquid is accelerated and the local pressure is lower than the vapor pressure of the liquid, flow rate and pressure are particularly important. From this, the basic dimensionless number representing the cavitation state, the cavitation number σ, is defined as shown in the following equation (4) edited by Yoji Kato, new edition of cavitation basics and recent advances, Tsuji Shoten, 1999 ).

Here, a large number of cavitations indicates that the flow field is in a state where cavitation is difficult to occur. In particular, when cavitation is generated through a nozzle or orifice pipe such as a cavitation jet, the cavitation number σ is expressed by the following equation 5 from the nozzle upstream pressure p ₁ , the nozzle downstream pressure p ₂ , and the saturated vapor pressure p _{v of the} sample water. In the cavitation jet, the pressure difference between p ₁ , p _{2, and} p _v is large, and p ₁ >> p ₂ >> p _v. (H. Soyama, J. Soc. Mat. Sci. Japan, 47 (4), 381 1998).

  The cavitation condition in the present invention is preferably such that the cavitation number σ is 0.001 or more, 1 or less, preferably 0.003 or more and 0.5 or less, and particularly preferably 0.01 or more and 0.1 or less. When the cavitation number σ is less than 0.001, the effect is small because the pressure difference with the surroundings when the cavitation bubbles collapse is low, and when it is greater than 0.5, the flow pressure difference is low and cavitation is difficult to occur. .

  In addition, when the injection liquid is injected through the nozzle or the orifice pipe to generate cavitation, the pressure of the injection liquid (upstream pressure) is desirably 0.01 MPa or more and 30 MPa or less, and 0.7 MPa or more and 20 MPa or less. Is preferred. When the upstream pressure is less than 0.01 MPa, it is difficult to produce a pressure difference from the downstream pressure, and the effect is small. On the other hand, when the pressure is higher than 30 MPa, a special pump and a pressure vessel are required, and energy consumption increases, which is disadvantageous in terms of cost. On the other hand, the pressure in the container (downstream pressure) is preferably 0.05 MPa to 0.3 MPa in static pressure. Further, the pressure ratio between the pressure in the container and the pressure of the spray liquid is preferably in the range of 0.001 to 0.5.

  Further, the jet velocity of the jet liquid is desirably in the range of 1 m / second to 300 m / second, and preferably in the range of 20 m / second to 200 m / second. When the jet velocity is less than 1 m / second, the effect is weak because the pressure drop is low and cavitation hardly occurs. On the other hand, if it is higher than 300 m / sec, a high pressure is required and a special device is required, which is disadvantageous in terms of cost.

  In the present invention, the cavitation generation place can be selected from any container such as a tank or inside a pipe, but is not limited thereto. Further, although it is possible to perform processing in one pass, the effect can be further increased by circulating the required number of times. Furthermore, it can be processed in parallel or in permutation using a plurality of generating means. The liquid injection for generating cavitation may be performed in an open-air container such as a pulper, but is preferably performed in a pressure container in order to control cavitation.

  In the method of generating cavitation by the liquid jet in the present invention, tap water, reused water recovered in the papermaking process, pulp squeezed water, white water, and the pulp suspension itself are used as the jet liquid for the pulp suspension. Although it can spray, it is not limited to these. Preferably, by injecting the pulp suspension itself, in addition to the effect of cavitation generated around the jet flow, a hydrodynamic shear force when jetting from a nozzle or orifice tube at high pressure is obtained, so that a larger effect is obtained. Demonstrate the effect.

  The solid content concentration of the pulp suspension to be treated when cavitation is generated by liquid jet is preferably 5% by weight or less, more preferably 4% by weight or less, and further preferably in the range of 0.1 to 3% by weight. It is preferable to treat from the viewpoint of bubble generation efficiency. When the solid concentration of the liquid to be ejected is 5 wt% or more and 20 wt% or less, the effect can be obtained by setting the concentration of the jet liquid to 4 wt% or less.

  The pH of the pulp suspension is preferably pH 1 to 13, more preferably pH 3 to 12, and still more preferably pH 4 to 11. If the pH is less than 1, corrosion of the apparatus becomes a problem, which is disadvantageous from the viewpoint of material and maintenance. On the other hand, when the pH exceeds 13, the alkali burn of the cellulose fiber occurs and the whiteness decreases, which is not preferable.

  In the present invention, by increasing the jetting pressure of the liquid, the flow velocity of the jetting liquid is increased, and the pressure is lowered accordingly, and stronger cavitation is generated. Further, by pressurizing the container for storing the liquid to be ejected, the pressure in the region where the cavitation bubbles collapse is increased, and the pressure difference between the bubbles and the surroundings is increased, so that the bubbles collapse violently and the impact force increases. Cavitation is influenced by the amount of gas in the liquid, and when there is too much gas, collision and coalescence of bubbles occur, so that a collapse impact force is absorbed by other bubbles, and the impact force is weakened. Therefore, the treatment temperature is preferably 0 ° C. or higher and 70 ° C. or lower, particularly 10 ° C. or higher and 60 ° C. or lower, because it is affected by dissolved gas and vapor pressure. In general, the impact force is considered to be maximum at the midpoint between the melting point and the boiling point, so in the case of an aqueous solution, around 50 ° C is suitable, but even at a temperature lower than that, it is not affected by the vapor pressure. Therefore, a high effect can be obtained within the above range.

  The papermaking raw material (papermaking raw material 1) containing pulp having scale-like external fibrils of the present invention contains fillers and other papermaking chemicals in addition to pulp. The pulp having the scale-like external fibrils and the filler and / or papermaking chemicals are mixed and then mixed with a papermaking raw material (papermaking raw material 2) containing pulp other than the pulp having the scale-like external fibrils. To do. The papermaking raw material 2 may contain fillers and / or papermaking chemicals, but among the fillers and / or papermaking chemicals contained in all papermaking raw materials, the fillers and / or papermaking contained in the papermaking raw materials 1 From the viewpoint of improving yield, it is preferable that the chemical for use is 50% by weight or more.

  The filler targeted by the present invention is not particularly limited as long as it is a particle generally called an inorganic filler and an organic filler. Specifically, as inorganic filler, calcium carbonate (light calcium carbonate, heavy calcium carbonate), magnesium carbonate, barium carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, clay (kaolin, calcined kaolin) Delamikaolin, talc, zinc oxide, zinc stearate, titanium dioxide, silica made from sodium silicate and mineral acid (white carbon, silica / calcium carbonate composite, silica / titanium dioxide composite), white clay, bentonite Diatomaceous earth, calcium sulfate and the like. Organic fillers include urea-formalin resin, polystyrene resin, phenol resin, fine hollow particles, acrylamide composites, wood-derived substances (fine fibers, microfibril fibers, powder kenaf), modified insolubilized starch, ungelatinized starch, etc. Is mentioned. These may be used alone or in combination of two or more.

  Other papermaking chemicals to be blended are conventionally used as internal sizing agents, dry paper strength enhancers, wet paper strength enhancers, flocculants, drainage improvers, colorants, dyes, fluorescent dyes, etc. Examples include internal additives, and paper bulking agents for increasing the paper bulk (lowering the density) .There is no particular limitation, but adding a cationic chemical among the flocculants increases the yield improvement of the filler. ,preferable.

  In the present invention, as a cationic chemical for fixing a filler to a pulp having flaky external fibrils, as an inorganic flocculant, sulfuric acid band (aluminum sulfate), aluminum chloride, PAC (polyaluminum chloride), ferric chloride, polysulfuric acid Examples include ferric iron. Organic flocculants include polyethyleneimine, polyalkyleneimine, dicyandiamide polymer, polyamine, polyamine / epichlorohydrin polymer, and dialkyl diallyl quaternary monomer, dialkylaminoalkyl acrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl acrylamide and dialkylaminoalkyl. Examples thereof include polymers of methacrylamide and acrylamide, polymers composed of monoamines and epihalohydrin, and mixtures thereof. Examples of the organic flocculant include acrylamide polymers and copolymers with the above cationic chemicals. Furthermore, in addition to these cationic chemicals, anionic or nonionic or amphoteric particles and polymers can be added as the second and third components. The addition rate of these cationic chemicals to the filler is 0.05 to 2.0 solids by weight.

  Specific examples of the bulking agent for paper include oil-based nonionic surfactants, sugar alcohol-based nonionic surfactants, sugar-based nonionic surfactants, polyhydric alcohol-type nonionic surfactants, polyhydric alcohols. And fatty acid ester compound, higher alcohol or polyoxyalkylene adduct of higher fatty acid, polyoxyalkylene adduct of higher fatty acid ester, polyoxyalkylene adduct of polyhydric alcohol and fatty acid ester compound, fatty acid polyamidoamine, etc. There is no particular limitation.

  The mixing method of the pulp having scale-like external fibrils and the filler and / or papermaking chemicals is not particularly specified, and both can be mixed in a tank or a chest. The above-mentioned pulp slurry can be added to the filler slurry. As a mixing method, it is possible to mix in a pipe using an in-line mixer or the like.

  As the time for mixing the pulp having scale-like external fibrils and the filler and / or the papermaking chemical, when the cationic chemical is not added, mixing with stirring for 5 minutes or more is necessary. It is considered that contact between the filler and the fiber occurs by stirring for a certain time, and the filler is adsorbed on the fibrils. On the other hand, when a cationic chemical is added and mixed efficiently, fixing of the filler occurs instantaneously, so that a particularly long time is not required.

  The blending ratio of the pulp having scale-like external fibrils to the total pulp is not particularly limited, but is preferably 10% by weight to 50% by weight. If the solid content is less than 10% by weight, the ratio of the pulp having flaky external fibrils to the pulp having flaky external fibrils is too low to clarify the yield improvement effect. This is disadvantageous because it increases the cost of chemicals.

  The blending ratio of the filler with respect to the total pulp is 2 to 30% by weight, more preferably 5 to 30% by weight. If it is less than 2% by weight, the yield improvement effect is small, and if it exceeds 20% by weight, it becomes difficult to make paper.

  Examples of the pulp other than the pulp having scale-like external fibrils include kraft pulp of conifers and hardwoods, chemical pulp such as sulfite pulp, crushed pulp of conifers and hardwood, refiner crushed pulp, thermomechanical pulp, chemithermomechanical pulp, etc. These include mechanical pulp, recycled pulp derived from sheet-like substances made of used paper and fiber, and these may be unbeaten products or beaten products by conventional techniques such as refiners, kneaders, and dispersers.

  The paper machine to which the paper manufacturing method of the present invention can be applied is not particularly limited, and examples thereof include a long net type, an on-top twin wire type, a gap former type, a circular net type, and a multilayer type. A surface treating agent may be applied for the purpose of improving the surface strength and imparting water absorption resistance. When applying a surface treatment agent, there is no particular limitation on the components of the surface treatment agent, and there is no limitation on the size press type, and the size of the liquid film transfer system such as a 2-roll size press, a gate roll size press, or a shim sizer. A press or the like can be used as appropriate. Further, for the purpose of smoothing the surface of the paper, the treatment may be performed using a known calendar device such as a machine calendar, a soft nip calender, or a high temperature soft nip calender.

  The paper obtained by the present invention is not limited to the type and basis weight of the paper, and further includes various base papers and paperboard. There is no limitation on the ash content in the paper. In addition to single-layer paper, multi-layer paper having two or more layers may be used.

[Action]
When the papermaking raw material prepared by mixing pulp having scale-like external fibrils and filler and / or papermaking chemicals is mixed with the papermaking raw material containing pulp other than the pulp having scale-like external fibrils to make paper Improved yield of fillers and / or papermaking chemicals in the paper making process compared to mixing papermaking materials prepared by mixing pulp, fillers and / or papermaking chemicals prepared by conventional beating methods The present inventors presume the mechanism that can be made as follows. Fillers and papermaking chemicals are usually preferentially adsorbed to external fibrils and fine fibers over the pulp fiber body, and especially fillers and papermaking chemicals adsorbed to fine fibers pass through the paper machine wire and cause a decrease in yield. Become. In contrast, fillers and papermaking chemicals adsorbed on external fibrils are prevented from passing through the paper machine wire. In the present invention, a pulp having scale-like external fibrils is efficiently produced, and this is mixed with a filler and / or a paper-making chemical, so that the external fibril portion of the pulp having scale-like external fibrils is used for filler or papermaking. It is thought that the yield is improved because the chemicals adsorb efficiently.

The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to such examples.
<Manufacture of pulp>
A sample (raw material A) was collected from the inlet of a beating machine (double disc refiner: manufactured by Aikawa Tekko Co., Ltd.) from the preparation process of hardwood bleached kraft pulp manufactured at the factory. Using the cavitation jet cleaning device described in Japanese Patent Application No. 2005-321231, the pressure of the jet liquid (upstream pressure) is 7 MPa (jet flow velocity 70 m / sec), and the pressure in the jetted container (downstream pressure) ) Was set to 0.3 MPa and adjusted to an arbitrary freeness. Note that a pulp suspension having a concentration of 1.1% by weight was used as the spray liquid, and the pulp suspension (concentration of 1.1% by weight) in the container was subjected to cavitation treatment. The obtained sample was used as a raw material B.

  On the other hand, the raw material exit material at the time of collecting the raw material A was used as the raw material C.

The raw material B and the raw material C were dried in a state where fibers were swollen without forming a hydrogen bond by a solvent substitution method according to Stone et al. It was.
[Measurement of area ratio of external fibril part]
The area ratio of the external fibril portion of the cavitation-treated pulp was measured by the procedure shown below.
1. The long fiber part (42 mesh on) of the pulp is fractionated and used as a sample.
2. Wash the long fibers of the pulp with distilled water.
3. The long fibers of the pulp are dyed using a dyeing solution (Orange dye (PONTAMINE FAST ORANGE 6RN): Direct Blue-1 = 0.2: 1).
4). The long fibers of the dyed pulp are washed in distilled water.
5. A long sheet of pulp is sucked onto the filter and dehydrated to prepare a measurement sheet.
6). After drying the measurement sheet, a photograph of long fibers of the pulp is taken using an ultra-deep color 3D shape measurement microscope (trade name: VK-9500 Generation II, manufactured by Keyence). At this time, the external fibril portion is dyed orange and the fiber is dyed blue.
7). From the micrograph of the fiber, select the externally fibrillated fiber, and calculate the area of the external fibril part and the area of the fiber part with the image analysis processing software (particle analysis application VK-H1G9 attached to the microscope). The area ratio of the external fibril portion is calculated by the following formula 6.

In the electron micrograph shown in FIG. 1, in the raw material C, the fluff called fibrils on the fiber surface is thread-like, but in the raw material B, the entire fiber surface is thinly peeled off. This is an aggregate of microfibrils on the fiber surface peeled off in a scaly manner.
Table 1 shows the freeness and the external fibril area ratio of the raw materials B and C.

<Examples of yield and comparative examples>
[Example 1]
40 wt% of light calcium carbonate (TP121BM, manufactured by Okutama Kogyo Co., Ltd.) and 10 wt% of titanium dioxide (B101S, manufactured by Nihon Talc Co., Ltd.) are added to the raw material B and stirred for 10 minutes. Got. Thereafter, the raw material D and the raw material C were mixed at a ratio of 50/50 in terms of solid content weight. The filler content in the final total solids is about 17% by weight. To the mixed suspension, a sulfuric acid band was added and mixed so as to be 1.0% by weight of the total solid content, thereby preparing a paper stock. Table 2 shows the results of measuring the yield of the filler by the method described below.
[Filling yield measurement method]
The yield of the filler was measured under the following conditions using a dynamic drainage jar (DDJ).
Equipment: Improved DDJ (with baffle, 200 mesh wire), rotation speed: 800 rpm
Procedure: Take the stock (0.5 wt%, absolutely dry 2.5g) in DDJ, start filtering after stirring for 40 seconds, collect filtered water for 30 seconds from 5 seconds after starting filtering, By obtaining the ash content, the filler yield was calculated by the following formula 7.

[Comparative Example 1]
40 wt% light calcium carbonate (TP121BM, manufactured by Okutama Kogyo Co., Ltd.) and 10 wt% titanium dioxide (B101S, manufactured by Nihon Talc Co., Ltd.) are added to the raw material C instead of the raw material B, The mixture was stirred for 10 minutes to obtain raw material E. Then, the raw material E and the raw material C were mixed in the ratio of 50/50 by solid content weight. The filler content in the final total solids is about 17% by weight. A paper material was prepared by adding and mixing a sulfuric acid band to the mixed suspension so that the total solid content weight was 1.0% by weight. The results are shown in Table 2.

[Comparative Example 2]
To the raw material C, 17 wt% of a mixed filler obtained by mixing light calcium carbonate (TP121BM, manufactured by Okutama Kogyo Co., Ltd.) and titanium dioxide (B101S, manufactured by Nippon Talc Co., Ltd.) at a ratio of 4 to 1, Stir for 10 minutes. A suspension was prepared by adding and mixing a sulfuric acid band to 1.0% by weight of the solid content per total solid weight.

[Example 2]
A paper material was prepared and evaluated in the same manner as in Example 1 except that the mixing ratio of the raw material D and the raw material C was 30/70 and the filler content in the final solid content was about 10% by weight. It was. The results are shown in Table 2.

[Comparative Example 3]
A stock was prepared and evaluated in the same manner as in Example 2 except that the mixing ratio of the raw material E and the raw material C was 30/70. The results are shown in Table 2.

[Comparative Example 4]
Except for the addition of 10% solids by weight, a mixed filler prepared by mixing light calcium carbonate (TP121BM, manufactured by Okutama Kogyo Co., Ltd.) and titanium dioxide (B101S, manufactured by Nihon Talc Co., Ltd.) at a ratio of 4 to 1 to the raw material C In the same manner as in Example 2, the paper stock was adjusted and evaluated. The results are shown in Table 2.

[Example 3]
The material was prepared and evaluated in the same manner as in Example 1 except that polydiallyldimethylammonium chloride as a cationic chemical was added in an amount of 0.2% by weight based on the solid content of the filler when mixing the raw material D and the filler. It was. The results are shown in Table 2.

[Comparative Example 5]
The stock was prepared and evaluated in the same manner as in Example 3 except that the raw material E was used instead of the raw material D. The results are shown in Table 2.

[Comparative Example 6]
Except for the addition of 10% solids by weight, a mixed filler prepared by mixing light calcium carbonate (TP121BM, manufactured by Okutama Kogyo Co., Ltd.) and titanium dioxide (B101S, manufactured by Nihon Talc Co., Ltd.) at a ratio of 4 to 1 to the raw material C Evaluated the paper stock in the same manner as in Example 3. The results are shown in Table 2.

From the results in Table 2, it can be seen that Example 1 has a better filler yield than Comparative Examples 1 and 2. Similarly, Example 2 and Example 3 had higher filler yields than Comparative Examples 3 and 4, and Comparative Examples 5 and 6, respectively.

<Examples of paper and comparative examples>
[Example 4]
A handsheet was made from the raw material of Example 1 based on JIS P 8222. The thickness and basis weight of the handsheet were measured by the following method, and the density was calculated based on this. Furthermore, ISO opacity, ISO whiteness, specific scattering coefficient, and formation coefficient were measured by the following methods. The results are shown in Table 3.
[Paper quality measurement method]
-Paper thickness: According to JIS P 8118: 1998.
-Basis weight: According to JIS P 8124: 1998 (ISO 536: 1995).
Density: Calculated from the measured values of the hand-sheet thickness and basis weight.
ISO opacity: in accordance with JIS P 8149: 2000
ISO whiteness: measured with a color difference meter (manufactured by Murakami Color) in accordance with JIS P 8148.
-Formation coefficient: The formation of paper was evaluated by the total land FMT-III (light transmission fluctuation method) manufactured by Nomura Corporation. In addition, it shows that a formation is so favorable that a measured value is small.

[Comparative Example 7]
Evaluation was performed in the same manner as in Example 4 except that the paper stock of Comparative Example 1 was used. The results are shown in Table 3.

[Example 5]
Evaluation was performed in the same manner as in Example 4 except that the paper stock of Example 2 was used. The results are shown in Table 3.

[Comparative Example 8]
Evaluation was performed in the same manner as in Example 4 except that the paper stock of Comparative Example 3 was used. The results are shown in Table 3.

[Example 6]
Evaluation was performed in the same manner as in Example 4 except that the paper stock of Example 3 was used. The results are shown in Table 3.

[Comparative Example 9]
Evaluation was performed in the same manner as in Example 4 except that the paper stock of Comparative Example 5 was used. The results are shown in Table 3.

From the results of Table 3, it can be seen that Examples 4, 5, and 6 have higher opacity and whiteness than those of Comparative Examples 7, 8, and 9, respectively, and the formation is good.

It is an electron micrograph (1000 times) of the raw material B and the raw material C.

Claims (4)

  A papermaking raw material prepared by mixing a pulp having scale-like external fibrils and a filler and / or papermaking chemicals is mixed with a papermaking raw material containing pulp other than the pulp having a scale-like external fibril to make paper. A paper manufacturing method characterized by the above.   A papermaking raw material prepared by mixing a pulp having scale-like external fibrils and a filler and a cationic chemical is mixed with a papermaking raw material containing pulp other than the pulp having scale-like external fibrils, and papermaking is characterized. Paper manufacturing method.   As pulp having scale-like external fibrils, it is possible to use pulp obtained by generating bubbles by cavitation in the pulp suspension in the reaction tank and applying impact force generated when the bubbles collapse to the pulp fibers. The method for producing paper according to claim 1 or 2.   Paper obtained by the paper manufacturing method according to any one of claims 1 to 3.

Images